(1) Field of the Invention
The present invention relates to the fabrication of integrated circuit devices, and more particularly, to a method of improving the gap filling characteristics of the dielectric layer during metallization in the fabrication of integrated circuits.
(2) Description of the Prior Art
In the fabrication of integrated circuit devices, semiconductor device structures such as gate electrodes and source and drain regions are typically formed in and on a semiconductor substrate. An insulating layer is deposited over the surface of the substrate and planarized. Next, a metal conducting layer is deposited and patterned to contact the underlying semiconductor device structures. A dielectric layer is deposited overlying the metal conducting layer and further conducting layers may be formed. As the packing density of semiconductor devices increases, the size of the gap between the patterned metal areas decreases. FIG. 1 illustrates a partially completed integrated circuit device. Semiconductor substrate 10 which may contain semiconductor device structures and a planarized insulating surface 11 is shown. Metal layer 12 has been deposited and patterned. Gap 15 between the patterned metal areas is to be filled by dielectric layer 14. The dielectric layer 14 is typically a tetraethoxysilane (TEOS) oxide deposited by chemical vapor deposition (CVD). This deposition technology is subject to arrival angle effect or shadowing effect. That is, the deposition rate of the dielectric material is faster in the corner regions 16 than in other regions. If the oxide thickness is large enough, the corner portions of the dielectric material 16 will meet causing a void to form within the gap. This is detrimental to device operation. It is desired to find a gap-filling technique which will completely fill a gap between patterned metal areas without the presence of voids.
U.S. Pat. No. 4,872,947 to Wang, U.S. Pat. No. 5,069,747 to Cathey et al, and U.S. Pat. No. 5,231,058 to Maeda et al describe O.sub.3 -TEOS or O.sub.3 -OMCTS processes. The patent to Cathey et al uses dilute HF to remove O.sub.3 -TEOS structures. U.S. Pat. No. 5,169,791 to Muenzer discloses the passivation of crystal defects using atomic hydrogen. U.S. Pat. No. 5,194,397 to Cook et al and U.S. Pat. No. 5,089,441 to Moslehi disclose the use of HF to remove native oxide. The paper, "Dependence of Film Properties of Subatmospheric Pressure Chemical Vapor Deposited Oxide on Ozone-to-Tetraethylorthosilicate Ratio" by Judy Huang et al, J. Electrochem. Soc., Vol. 140, No. 6, June 1993, pp. 1682-1686, states that subatmospheric pressure chemically vapor deposited (SACVD) oxide can fill a gap of 4000 Angstroms between metal lines.